Array with Size Increment / Decrement
The Add Mesh: Extra Objects addon has a step pyramid mesh. However, it has a maximum of 20 steps. That can be fixed though, by editing the script file.  

The location of the addon's initialisation script is shown in the User Preferences window (see the image below, the part marked in green; this shows the location in my installation, and it may differ depending on what OS you're running). The script for the step pyramid is called add_mesh_pyramid.py, and it should be located in the same directory as the &#95;&#95;init&#95;&#95;.py file.
Open the file, locate num_steps and simply change the max value to something that works for you. With hundreds of steps, you may also need to change the min value of reduce_by to something lower.  

To activate it, CtrlAltU to go to user preferences. Click the Add-ons tab, then Add Mesh, then the little check box to the right at Add Mesh: Extra Object. If you want the addon to remain after you close Blender, also click Save User Settings.  

  

I haven't been able to get screenshots from Blender to capture the menus, so I can't show you, but the step pyramid will be available under Add > Mesh > Misc Objects > Step Pyramid. Here's the available settings to tweak it.